Room temperature interfacial reaction-directed synthesis of hierarchically porous ceria from a water-soluble precursorElectronic supplementary information (ESI) available: A TEM image of the Ce2(SO4)3 precursor under higher magnification, nitrogen adsorption-desorption isotherm and the corresponding BJH pore size distribution for the C-ceria sample, and the curve-fitting of O 1s and Au 4f XPS spectra. See DOI: 10.1039/c5ta00664c

Unlike the conventional calcination of cerium precursors at elevated temperature, hierarchically porous ceria was successfully synthesized via an interfacial reaction between the water-soluble cerium sulfate (Ce 2 (SO 4 ) 3 ) precursor and NaOH in ethanol at room temperature. Neither additional surfactant molecules nor calcination was employed during the whole preparation process. It was found that the as-prepared ceria inherited well the shape and dimensions of the hierarchically flowerlike Ce 2 (SO 4 ) 3 precursor after the interfacial reaction. The concentration of sulfuric acid was demonstrated to play a great role in controlling the precursor's morphology. Compared with ceria derived from direct calcination of the same Ce 2 (SO 4 ) 3 precursor, the one obtained from the interfacial reaction was far more reactive in CO oxidation due to its well-retained hierarchically porous morphology and high surface area. This work is expected to open a new, simple avenue for the synthesis of hollow nanomaterials from water-soluble precursors. Hierarchically porous ceria was successfully synthesized via an interfacial reaction between the water-soluble Ce 2 (SO 4 ) 3 precursor and NaOH in ethanol. Neither additional surfactant molecules nor calcination was employed during the preparation process.